noun.
An orange-red to grayish yellow mixture of several uranium oxides, silicates, and salts occurring naturally in the oxidation and hydration of uraninite.
The Century Dictionary and Cyclopedia
noun.
An orange-yellow mineral consisting chiefly of hydrous oxid of uranium, produced by the alteration of uraninite.
the GNU version of the Collaborative International Dictionary of English
noun.
A yellow amorphous mineral, essentially a hydrated oxide of uranium derived from the alteration of uraninite.